盐间页岩油储层基质孔隙内盐赋存状态  

Salt Occurrence in Matrix Pores of Intersalt Shale Oil Reservoirs

作　　者：杨柳[1] 鲁环宇 范鑫 黄志文[2] 周彤[2] YANG Liu;LU Huan-yu;FAN Xin;HUANG Zhi-wen;ZHOU Tong(State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology(Beijing),100083 Beijing,China;Institute of Petroleum Exploration and Development,China Petrochemical Corporation,Beijing 100083,China)

机构地区：[1]中国矿业大学(北京)深部岩土力学与地下工程国家重点实验室,北京100083 [2]中国石油化工股份有限公司石油勘探开发研究院,北京100083

出　　处：《科学技术与工程》2020年第5期1839-1845,共7页Science Technology and Engineering

摘　　要：潜江凹陷盐间页岩地层是中国潜力巨大的高效烃源岩,在高封闭性、强蒸发、干湿气候交替环境下形成的。页岩油以吸附态在页岩地层中储存,潜江凹陷页岩油储量丰富,广泛发育的盐韵律层系为页岩油的开采造成较大困难,盐间页岩储层含盐量高,盐间页岩中的盐遇水后会发生溶解等强相互作用,导致孔隙结构发生剧烈变化,然而目前对于盐间页岩中盐的赋存状态及含量尚不清楚。深入研究潜江凹陷盐间页岩盐赋存状态,对实现页岩油有效开发具有重要意义。针对白云质页岩、钙芒硝质页岩和泥页岩3种盐间页岩油储层样品,通过肉眼、显微镜和扫描电镜观测盐晶体的形态及分布特征,建立起一种定量评价页岩储层盐离子扩散能力的方法。结果显示,盐间页岩油储层中盐离子主要以晶体的形式分散于岩石内部,是岩石骨架结构的一部分。白云质页岩中盐晶体主要以团状聚集的形式存在,钙芒硝质页岩中盐晶体颗粒分布较为均匀,泥质页岩盐晶体主要充填于层理弱面中。浸没在水中的盐间页岩中的盐离子迅速溶解并扩散进入水中,溶液电导率从初始电导率G 0开始缓慢增加,初期增加较快,后期曲线逐渐趋于平缓。然而,溶液电导率与时间t的平方根的线性关系较差,这与盐间页岩盐晶体溶解影响了孔隙结构,进而影响到了盐离子的扩散速率有关。钙芒硝页岩盐离子扩散速率最大,约为白云质页岩的1.5倍,约为泥质页岩的3倍。此外,盐间页岩油储层的离子扩散速率大大高于海相、陆相页岩气储层,为15~45倍。理解盐间页岩的盐赋存特征对认识页岩油储层与水的相互作用和提高页岩油的产出具有重要意义。The intersalt shale formation in Qianjiang sag is a highly efficient source rock with great potential in China,which is formed under the alternating environment of high sealing,strong evaporation and dry and wet climate.Shale oil is stored in shale formation in adsorbed state.Qianjiang sag is rich in shale oil reserves.The widely developed salt rhythm layer system causes great difficulties for shale oil exploitation,and the salt content of intersalt shale reservoir is high.Salt in intersalt shale will dissolve and other strong interaction will occur with the presence of water,resulting in drastic changes in pore structure.However,the occurrence state and content of salt in intersalt shale are not clear.In-depth study of the occurrence state of intersalt shale salt in Qianjiang sag is of great significance for the effective development of shale oil.The morphology and distribution characteristics of salt crystals were observed by naked eye,microscope and scanning electron microscope for three kinds of intersalt shale oil reservoir samples of dolomitic shale,calcium mirabilite shale and shale.A method for quantitative evaluation of salt ion diffusion in shale reservoir was established.Results show that the salt ions in the intersalt shale reservoir are mainly dispersed in the form of crystals and are part of the rock skeleton structure.The salt crystals in dolomite shale mainly exist in the form of cluster aggregation,the salt crystal particles in calcium mirabilite shale are evenly distributed,and the argillaceous shale salt crystals are mainly filled in the weak bedding plane.The salt ions in the intersalt shale immersed in water are rapidly dissolved and diffused into water.The conductivity of the solution increases slowly from the initial conductivity G 0,increases rapidly at the initial stage,and tends to be smooth in the later stage.However,the linear relationship between solution conductivity and t is poor,which is related to the fact that the dissolution of shale salt crystals affects the pore structure and

关 键 词：页岩油 离子扩散 盐间页岩 返排率 

分 类 号：TE348[石油与天然气工程—油气田开发工程]